Fuse.



` will eliminate the danger of explosion and4 A multiple lli-nk fuse wh-ich embodies ,ing

EDWARD E. ROBERTS, HARTFORD, CONNECTICUT.

FUSE.

To all whom. 15 may concern Be it known that I, EDWARD E. ROBERTS, a citizen of the .United States, and a resident of Hartford, in the county of Hartford and State of Connecticut, have invented a new and Improved Fuse, of which the following is a full, clear, and exact description.

This invention relates to inclosed electric safety fuses. Fuses of this character have one or more fusible links inclosed in an insulating casing andgsurr'ounded by a granu lar, pulverized or fioc'culent non-conducting material which is provided to dilfuse and retard the flow of the hot gases that are evolved when the fusible link or links are changed from a solid stat-e to a gaseous condition, and thus while allowing the escape of thc gases so cooling them that the possi bility of explosion is eliminated and the outflow of flame and molten metal, which would be liable to cause disastrous conflagration, is prevented.

The object of this invention isto so construct a fuse of this nature that many restricted paths are provided for the hot gases evolved by the fusion of the metal whereby the gases will be dispersed throughout the filling material and the arc quickly quenched7 and yet at the same time to providea relatively free passage for the outflow of the cooled gases and also the air that is' between the particles of filling material and that is expelled by the gases at the instant the fuse blows. To accomplish this lend the interior ofthe casing which incloses one or more fusible links is divided into two lor more compartments. In th'c compartmentor compartments containing a. fusible link is a granular non-conducting material of relatively fine particles for th'e purpose of absorbing and thoroughly diffusand cooling the gases evolved by the volatilization of the metal and smothering the arc. In the other compartment or compartments is a granular non-conducting material in a relatively coarser state, which provides an easier path for the escape of the gases and also the'air between the particles which is expelled by the gases, andv thus insu-ring a rapid reduction of internal pressure which cause a quick and safe opening of' thel circuit.

IlFi'gur'e I of the accompanying' drawingsshows a central longitudinal section of a this in- Specicaton of Letters Patent. Applieauan' aies December 2s, 1911.

Patented Nov. 4, 1913. Serial No. 668,354.

vention. Fig. 2 shows a transversesection of the same on the plane indicated by the dotted line 2 2 on Fig. l. Fig. 3 shows a central longitudinal section of a single flat strip'link fuse which embodies the invention. Fig. 4. shows a transverse section of the single link fuse on the plane indicated by the dotted line A on Fig. Fig. 5 shows a central longitudinal section of a modification of a single link fuse which embodies the invention. Fig. 6 shows a transverse section of t-he fuse shown in Fig. 5 on the plane indicated by the dotted line Fig. 7 is a fragmentary View showing how openings may be made in an inner tube.

The fuses illustrated are of the ferrule contact type, but the invention isv not limited to fuses of this type. In the form lirst shown the fusehas a tubular casing l0 which is preferably made of vulcanized fiber. The ends of the casing are closed by end Caps ll which may be made of brass or any other suitable conducting material. In this casing four round fusible links 14 are shown, although the invention is not limited to the number of or the shape of the links. These links at their ends are connected with the internal terminals l5 which are commonly made of copper and are secured to the end caps so as to form a close electrical connection therewith. In this form there is an inner tube 12 which can be made of vulcanized fiber or any other suitable electrical insulatingmaterial. The inner tube has openings 13- through its side near the middle. Through the end caps at the ends of the inner tube it is desirable to have vents 17.

The inner tube is filled with an electrical non-'conducting material 18x of relatively coarse grains. This coarse material is per# mitted to flow through theopenings in the tube and to surround the middle fusible links. The remainder of the4 space between the inner and outertubes and aroundl the fusible links and inner terminals is filled with an'electri'cal non-conducting material of relatively finer grains. As a result of this construction the fusible links tend to' rupture first at the middle owing to the fact that the coarse material does not conduct away the heat as readily as the fine material, and because of the larger air spaces and molten metal, the gases and air through the coarse material, the gas pressure will be reduced at the middle when the metal vaporof the easier course for the izes. For these reasons the fuse opens quickly and quietly without danger of bursting or t-he expulsion of fiame and molten metal.

In the second form shown there is but a single flat strip fusible link 14C provided with the usual calibration opening 11C. In this form the outer tubular casing 10L1 is made of insulating tubing and provided with metallic end 'caps 11. The interior of this casing is separated into two chambers by the inner insulating tube 12a. The inner tube has openings 13 through its side near the middle, which provide communication from one chamber to the other. It is desirable to vent the casing outside of the inner tube by making openings 17b through the end caps. Between the inner and outer tubes and in the openings through the inner tube is filled the relatively coarse non-conducting granular materialvlS, and in the remaining space in the inner tube about the fusible link and inner terminals a relatively finer non-conductinof granular material 1.) is filled. In this form of fuse the coarse material provides a relatively easy path for the gases developed when the element fuses so as to relieve the tension while the finer material absorbs the remaining gases and smothers the arc. l

In Fig. 5 the fusible link 14h is shown as a single round wire electrically connected with the caps 11b which close the ends of the outer tubular insulating casing 10b. EX- tending from end cap to end cap in this form of fuse are two insulating tubes 12b which have openings 13D through their sides near the middle. In this case vent holes 171 are made through the end caps opposite the ends of the inner tubes 12". Non-conducting material 1Sb of relatively coarse grain is filled into the inner tubes 12b and through the openings and about the middle of the fusible link. space about the link and innertubes is nonconducting material 19b in a relatively fine state. In this case a comparatively easy path is provided for the cooled gases through the coarse material in the inner tubes and out through the vent openings at the ends, leaving the finer material to absorb the molten metal, and quench the arc.

In a fuse constructed according to this invention the relatively coarse granular non-conducting material provides a comparatively easy ath for the hot gases and molten metal wiien the link or links first melt and also an' easy path for the air which is driven out by the generated gases. The path, however, about the coarse particles is sufficiently tu-tuous to cool the gases and absorb the molten metal so that nothing dangerous escapes from the casing when the fuse blows. As the links melt back, the finer filling material provides more ofl an Disposed in the remaining obstruction to the fiow of gas and molten metal and there are more spaces for absorbing the gases, and as the pressure has been relieved by the first fiow of the gases and air out through the coarse material, the following gases are readily absorbed inthe `spaces between the grains of the finer material, and if not completely absorbed they are so cooled by passing through the finer material that they will flow out through the coarser material without dangerous effect. A fuse constructed in this manner, whether of the single link or multiple link type arranged in a casing that is divided in the interior into two or more chambers, one of which is filled with material that provides a relatively easy path for the gases, will open quickly at the desired time without danger of explosion or discharging flames or molten metal to the atmosphere.

The invention claimed is:

1. In a fuse, a casing having two pase sages with an opening from one to the other, a fusible member in one of the passages, a non-conducting granular filling in the lastmentioned passage, and a coarser non-conducting granular filling in the other passage, the coarser filling extending through said opening to the fusible member.

2. In a fuse, a casing having two pas sages with an opening from one to the other, a fusible member in one of the passages, a non-conducting granular filling in the lastmentioned passage, and a coarser non-conducting granular filling in the other passage.

3. In a fuse, a casing having two passages with an opening from one to the other, a fusible member in one of the passages, a non-conducting granular filling in the lastmentioned passage, and a coarser non-conductinr granular filling in the other passage, t e passage containing the coarser filling being vented to the atmosphere.

4. In a fuse, a casing having two passages with an opening from one to the other, and a fusible member in one of the passages, said passages being respectively filled with granular non-conducting material of different degrees ofgranulation.

5. A fuse having a casing interior into a plural number of communieating chambers, a fusible member in one of the chambers, a non-conducting granular material about the fusible member, and a non-conductingI granular material of coarser granulation which will permit the easier escape of the gas in the other chamber.

6. A fuse havin@ a casing, a fusible element, and non-conducting granular material filling the easing about the fusible element, said non-conducting material having grains of different sizes, the finer surrounding the fusible element near its ends and the coarser surrounding the fusible element near Aits middle and providing an easier path for the divided in the v How of the member therein,

vdeveloped on the vmember.

gases developed on the melting of the .fusible member, than through the finer material.

7. A fuse having a vented casing, a fusible a non-conducting granular material disposed about the fusible member, and a relatively coarser non-conducting granular material surrounding the middle of the fusible element and leading to the vents in the casing, said coarser material serving as a means of escape for the gases melt-ing of the fusible 8. A fuse having two longitudinal passages with an opening intermediate the ends providing communication from one passage to the other, a non-conducting granular material filled in one of the passages, a fusible member disposed in the said passage, and a relatively coarser non-conducting granular .material filled in the other passage and extending through said opening to the fusible member. v

9. In a fuse, two tubes, one disposed wit-hin the other, there being an opening in the inner tube communicating with the space between the inner granular material filling the tubes,

the fil lng material on one side of the wall of the inner tube being coarser than that on the other side, and a fusible member extending through the finer filling.

10. In a fuse, two tubes, one disposed within the other, there being an opening in the inner tube affording communication from the inner tube to the space between the inner granular material filling the tubes, the filling on one side of the wall of the inner tube being coarser than that on the other side, a fusible member extending through the finer filling, and heads closing the ends of the outer tube, said heads having vents communicating with the coarser filling material.

In testimony whereof I have signed my nameto this specification in the presence of two subscribing witnesses.

EDWARD E. ROBERTS.

Witnesses:

ARTHUR B. PECK, HAROLD J. HAYWARD.

and outer tubes, non-conducting 

